Pregnancy in platelet-type VWD: A case series

Inherited platelet disorders in women

Inherited platelet disorders (IPD) are a heterogeneous group of hemorrhagic diseases affecting both men and women, but usually associated with more evident bleeding symptoms in women due to the exposure to sexspecific hemostatic challenges, like menstruation and delivery. Indeed, up to 50% of women presenting with menorrhagia are diagnosed an IPD, moreover women with IPD can have ovulation-associated bleeding events and are at higher risk of endometriosis. Large retrospective studies have shown that women with IPD have a significantly increased risk of post-partum hemorrhage, predicted by a high bleeding score at previous history and by a platelet count below 50X10⁹/L. In addition, in patients with IPD, female sex was associated with a higher frequency of excessive bleeding after surgery, even when excluding gynecological procedures. In conclusion, IPD may represent a serious problem for women's health, and their diagnosis and appropriate management is crucial to ensure female patients a good quality of life.

Menstrual and obstetrical bleeding in women with inherited platelet receptor defects-A systematic review

INTRODUCTION

Women with inherited platelet receptor defects (IPRD) may have an increased risk of heavy menstrual bleeding (HMB) and postpartum haemorrhage (PPH).

AIM

To present a systematic overview of the literature on the prevalence and management of menstrual and obstetrical bleeding in women with IPRD.

METHODS

Electronic databases were searched for original patient data on the prevalence and management of HMB and PPH in women with known IPRD or who were being investigated for IPRD.

RESULTS

Sixty-nine papers (61 case reports/series and 8 cohort studies) were included. Overall, studies were rated as 'poor quality'. The included cohort studies reported HMB in 25% (13/52) of women with Bernard-Soulier syndrome and in 22.1% (34/154) of women with Glanzmann thrombasthenia. In total, 164 deliveries in women with IPRD were described. Excessive bleeding occurred in 16.9% (11/65) of deliveries described in the largest cohort. PPH occurred in 63.2% (55/87) of deliveries described in case reports/series. PPH occurred in 73.7% (14/19) of deliveries that were not covered by prophylaxis compared with 54.2% (32/59) of deliveries that were (OR = 2.36, 95% CI 0.75-7.40). Neonatal bleeding complications were reported in 10.0% (8/80) of deliveries. In all (6/6) deliveries with neonatal bleeding complications wherein the presence of alloantibodies was investigated, either antiplatelet or anti-HLA antibodies were detected.

DISCUSSION/CONCLUSION

Menstrual and particularly obstetrical bleeding problems frequently occur in women with IPRD, based on small case reports and series of poor quality. International collaboration, preferably on prospective studies, is needed to improve clinical management of women-specific bleeding in IPRD.

Mechanisms of thrombocytopenia in platelet-type von Willebrand disease

Platelet-type von Willebrand disease is an inherited platelet disorder characterized by thrombocytopenia with large platelets caused by gain-of-function variants in GP1BA leading to enhanced GPIbα-von Willebrand factor (vWF) interaction. GPIbα and vWF play a role in megakaryocytopoiesis, thus we aimed to investigate megakaryocyte differentiation and proplatelet-formation in platelet-type von Willebrand disease using megakaryocytes from a patient carrying the Met239Val variant and from mice carrying the Gly233Val variant. Platelet-type von Willebrand disease megakaryocytes bound vWF at an early differentiation stage and generated proplatelets with a decreased number of enlarged tips compared to control megakaryocytes. Moreover, they formed proplatelets upon contact with collagen, differently from normal megakaryocytes. Similarly, collagen triggered megakaryocytes showed defective activation of the RhoA-MLC2 axis, which prevents proplatelet formation, and increased phosphorylation of Lyn, which acts as a negative regulator of GPVI signaling, thus preventing ectopic proplatelet-formation on collagen. Consistently, human and murine bone marrow contained an increased number of extravascular platelets compared to controls. In addition, platelet survival of mutant mice was shortened compared to control mice, and the administration of desmopressin, raising circulating vWF, caused a marked drop in platelet count. Taken together, these results show for the first time that thrombocytopenia in platelet-type von Willebrand disease is due to the combination of different pathogenic mechanisms, i.e. the formation of a reduced number of platelets by megakaryocytes, the ectopic release of platelets in the bone marrow, and the increased clearance of platelet/vWF complexes.

A novel D235Y mutation in the GP1BA gene enhances platelet interaction with von Willebrand factor in an Iranian family with platelet-type von Willebrand disease

Platelet-type von Willebrand disease (PT-VWD) is a rare bleeding disorder with an intrinsic defect in platelets rather than von Willebrand factor (VWF), but has clinical and laboratory features similar to the more common type 2B VWD. The intriguing nature of the pathophysiology and molecular genetics of PT-VWD has created lengthy debate in literature regarding its discrimination from type 2B VWD, and essentially confirming DNA analysis as the gold standard in diagnosis and revealing pathologic mutations. In this report we identify a novel Asp235Tyr mutation in the GP1BA gene of two Iranian patients showing the PT-VWD phenotype who were originally misdiagnosed as type 2B VWD. By structural modelling of the mutant by introducing Tyr235 into the available crystal structure of the glycoprotein (GP)Ibα N-terminal domain, we observed the mutant Tyr235 generates a hydrophobic tip to the extended β-switch loop of GPIbα. Further modelling of the resulting complex with VWFA1 indicates this could result in an enhanced interface compared to wild-type Asp235. This data provides an update to the present knowledge about this rare disorder, and confirms the necessity of genetic testing for accurate diagnosis, and the importance of studying natural mutations to better understand molecular aspects of GPIbα-VWFA1 interaction.

Systematic Analysis of Bleeding Phenotype in PT-VWD Compared to Type 2B VWD Using an Electronic Bleeding Questionnaire

Objective:

To investigate the utility of an electronic version of the condensed molecular and clinical markers for the diagnosis and management of type 1 von Willebrand disease (VWD) bleeding questionnaire (eBQ) in assessing the bleeding phenotype in platelet-type VWD (PT-VWD) and compare it to its closely similar disorder, type 2B VWD.

Methods:

Retrospective analysis of the clinical bleeding and laboratory phenotype of 13 patients with PT-VWD and 12 type 2B VWD.

Results:

Bleeding score (BS) was significantly lower in PT-VWD as compared to type 2B. Bleeding score correlated with platelet count and von Willebrand factor:Ristocetin cofactor activity in PT-VWD but not in type 2B with a significant reduction in platelet count in type 2B VWD compared to PT-VWD. The eBQ had sensitivity of 62% in PT-VWD and 92% in type 2B VWD.

Conclusion:

Objective analysis of bleeding symptoms further the understanding of the phenotype of 2 closely similar bleeding disorders for better diagnosis and follow-up. Larger international prospective studies are warranted to evaluate the utility of the eBQ in PT-VWD and other rare bleeding disorders.

Pseudo (platelet-type) von Willebrand disease in pregnancy: a case report

Background

Pseudo (platelet-type)-von Willebrand disease is a rare autosomal dominant bleeding disorder caused by an abnormal function of the glycoprotein lb protein; the receptor for von Willebrand factor. This leads to an increased removal of VWF multimers from the circulation as well as platelets and this results in a bleeding diathesis. Worldwide, less than 50 patients are reported with platelet type von Willebrand disease (PT-VWD).

Case presentation

We describe the management of platelet type von Willebrand disease in pregnancy of a 26 year old Caucasian primigravida. The initial diagnosis was made earlier following a significant haemorrhage post tonsillectomy several years prior to pregnancy. The patient was managed under a multidisciplinary team which included obstetricians, haematologists, anaesthetists and neonatologists. Care plans were made for the ante- natal, intra-partum and post-partum periods in partnership with the patient. The patient’s platelet count levels dropped significantly during the antenatal period. This necessitated the active exclusion of other causes of thrombocytopenia in pregnancy. A vaginal delivery was desired and plans were made for induction of labour at 38 weeks of gestation with platelet cover in view of the progressive fall of the platelet count. The patient however went into spontaneous labour on the day of induction. She was transfused two units of platelets before delivery. She had an unassisted vaginal delivery of a healthy baby. The successful antenatal counselling has encouraged the diagnosis of the same condition in her mother and sister. We found this to be a particularly interesting case as well as challenging to manage due to its rarity. Psuedo von Willebrand disease in pregnancy can be confused with a number of other differential diagnoses, such as gestational thrombocutopenia, idiopathatic thrombocytopenia, thrombotic thrombocytopenic purpura and pre-eclampsia; all need consideration during investigations even in a case such as this where the diagnosis of platelet type von Willebrand disease was known before pregnancy.

Conclusion

Management of pseudo von Willebrand disease in pregnancy involves the co-operation of multidisciplinary teams, regular monitoring of platelet levels and factor VIII and replacement as appropriate. This case report highlights this rare condition and the need to exclude all the other differential diagnoses of thrombocytopenia in pregnant women with thrombocytopenia.